1. Field of the Invention
The present invention relates to an apparatus for disposing of fuel-vapor, especially to an apparatus for disposing of fuel-vapor which can avoid mistaken learning of basic air-fuel ratio correction factors when purging of fuel-vapor evaporating from a charcoal canister is initiated.
2. Description of the Related Art
Fuel-vapor evaporating from a fuel tank is absorbed in a charcoal canister, and is properly purged into an inlet pipe, as fuel, in order to improve fuel consumption and to avoid air pollution.
However, because the fuel-vapor purged from the charcoal canister disturbs the air-fuel ratio control of an engine, a purge procedure which does not disturb the air-fuel ratio control must be applied.
Especially, it is very important that the air-fuel ratio control system having a learning function for a basic air-fuel ratio correction factors, in order to compensate for deterioration with age of an air-flow meter or fuel-injection valves associated with the engine, does not inhibit faulty learning of basic air-fuel ratio correction factors when purging of fuel-vapor evaporating from a charcoal canister is initiated.
Because a basic air-fuel ratio correction factor is generally learned for every driving region which is determined in accordance with the driving condition of the engine, a purge control system which inhibits purging when the engine is driven in a driving region where a basic air-fuel ratio correction factor has not been learned, has been already proposed (refer the Unexamined Patent Publication (Kokai) No. 62-206262).
However, because driving regions change in accordance with the driving conditions, purging is frequently interrupted if basic air-fuel ratio correction factors are not learned in many regions. This is not only defeats the requirement that purging must be continued as much as possible, but also causes mistaken learning.
Furthermore, when a large amount of fuel-vapor is stored in the charcoal canister, it is unavoidable that the air-fuel ratio is disturbed by frequent interruptions in the purging.